From: Ken Young (CiscoKid@ns.sympatico.ca)
Date: Sat Aug 25 2007 - 21:29:01 ART
R2 (AS2000)
----------fa0/0----------
| |
|e0 |fa0/0
R8 (AS8000) R1(AS1000)
|e1 |fa0/1
| |
----------fa0/0----------
R3 (AS3000)
eBGP Peerings:
R8--R2
R8--R3
R1--R2
R1--R3
Situation:
R8 is advertising 80.0.0.0/8 with all default attributes.
Result:
R2-2610XM#show ip bgp
Network Next Hop Metric LocPrf Weight Path
* 80.0.0.0 10.10.10.1 0 1000 3000 8000
i
*> 10.10.10.8 0 0 8000 i
R1-2611XM#show ip bgp
Network Next Hop Metric LocPrf Weight Path
* 80.0.0.0 10.10.10.8 0 2000 8000 i
*> 20.20.20.8 0 3000 8000 i
R1-2611XM#
R3-2610XM#show ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 80.0.0.0 20.20.20.8 0 0 8000 i
Question:
Why is R3 not seeing both paths? Is R1 not advertising the longer
path to R3 because it is aware that R3 already has a shorter path?
Even if that was the case I would have assumed both paths would be
seen by R3 but the shortest path via 8000 would be selected as best.
When I debug "ip bgp updates" R1 does not send an update to R3 for
that path unless, R3 sends a withdrawal of its existing path.
This archive was generated by hypermail 2.1.4 : Sat Sep 01 2007 - 11:32:13 ART